Documents: Special Interest: Water Gardening:

Filters for Your Pond
by David Wharton
September 18, 2014

 Choosing the right pond filter can be a tricky business, as, if the filtration is inadequate, your pond will not be thoroughly cleaned. This can leave to all kinds of problems, with water and fish health.

The Science Part

Before you choose a filter, it’s important to work out the correct size of your pond. This denotes the level of filtration that you will need.

Use this formula: Length x Width x Depth = Volume
For Example: 4m x 2m x 0.6m = 4.8m³ so the volume of the pond is 4800 litres

Once you know the volume of the pond, you then need to decide if you are keeping fish. If you do, the figure will need to be doubled to allow for sufficient filtration of fish waste and other debris.
Use the Sum of Volume x 2 = Filter Size needed.

So if we are working on a basis of 4800 litres, this is doubled to mean a 9600 litre filter is required.

However if you are going to keep Koi, it requires more work. A Koi pond requires 4 times the volume of filtration.
Volume x 4 = Filter Size needed. 4800 x 4 = 19200 litre filter is needed.

Now you have these figures, you can look at the best type of filter for your needs. There is a huge market for pond filters from leading manufacturers, so it can be a little confusing for even the most experienced pond keeper. Swell UK have a broad range of filters for all applications.

Pump and Filter Sets
Choose the right pump for the filter, it generally should match the capacity of the filter. This means that all of the water is treated per hour, ensuring the best results. If the filter is going to be higher than the pond then a pump with a higher level will provide a higher gravitational force. Here a pressurised pump and filter set is perfect as it contains everything needed for the height necessary.

Buying a pump and filter set can save money and time. They come with all the fittings needed and can be relatively simple to install. There are several types available to suit varying needs and budgets. Many contain UV clarifiers that treat the water with Ultra Violet light. This clumps together algae blooms and makes it easier for the filter to remove them.

In Pond Filters

Some filters can be positioned in the pond, which is great if you have a small garden or nowhere to put an external filter. Cables can be concealed easily in plants or other décor, so an in-pond filter can be a great space saver.

Again this type of filter can be purchased as part of a set with a pump, UV clarifier and even added extras such as fountain attachments. These are great for smaller ponds as everything you need is in one place.

Chamber Filters
These are ideal for Koi ponds that need a lot of filtration. The separate chambers each provide differing types of filtration including mechanical, biological and chemical to make sure that the water is clean and clear.

These large capacity filters sit externally to the pond so there must be adequate space to house it. These impressive pieces of kit can be costly, so it’s important to do your research before you buy.

For more advice and information speak to a reputable pond expert, who will be able to advise you as to the best product for your needs.

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